linux-kernel - Re: [PATCH v4 net-next 01/15] dt-bindings: ptp: add NETC Timer PTP clock

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Message-ID: <aKSMeI/mBmRxxDZt@lizhi-Precision-Tower-5810>
Date: Tue, 19 Aug 2025 10:38:48 -0400
From: Frank Li <Frank.li@....com>
To: Wei Fang <wei.fang@....com>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
	richardcochran@...il.com, claudiu.manoil@....com,
	vladimir.oltean@....com, xiaoning.wang@....com,
	andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, vadim.fedorenko@...ux.dev,
	shawnguo@...nel.org, s.hauer@...gutronix.de, festevam@...il.com,
	fushi.peng@....com, devicetree@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev, kernel@...gutronix.de
Subject: Re: [PATCH v4 net-next 01/15] dt-bindings: ptp: add NETC Timer PTP
 clock

On Tue, Aug 19, 2025 at 08:36:06PM +0800, Wei Fang wrote:
> NXP NETC (Ethernet Controller) is a multi-function PCIe Root Complex
> Integrated Endpoint (RCiEP), the Timer is one of its functions which
> provides current time with nanosecond resolution, precise periodic
> pulse, pulse on timeout (alarm), and time capture on external pulse
> support. And also supports time synchronization as required for IEEE
> 1588 and IEEE 802.1AS-2020. So add device tree binding doc for the PTP
> clock based on NETC Timer.
>
> It is worth mentioning that the reference clock of NETC Timer has three
> clock sources, but the clock mux is inside the NETC Timer. Therefore, the
> driver will parse the clock name to select the desired clock source. If
> the clocks property is not present, the NETC Timer will use the system
> clock of NETC IP as its reference clock. Because the Timer is a PCIe
> function of NETC IP, the system clock of NETC is always available to the
> Timer.
>
> Signed-off-by: Wei Fang <wei.fang@....com>
>
> ---
> v2 changes:
> 1. Refine the subject and the commit message
> 2. Remove "nxp,pps-channel"
> 3. Add description to "clocks" and "clock-names"
> v3 changes:
> 1. Remove the "system" clock from clock-names
> v4 changes:
> 1. Add the description of reference clock in the commit message
> 2. Improve the description of clocks property
> 3. Remove the description of clock-names because we have described it in
>    clocks property
> 4. Change the node name from ethernet to ptp-timer
> ---
>  .../devicetree/bindings/ptp/nxp,ptp-netc.yaml | 63 +++++++++++++++++++
>  1 file changed, 63 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml
>
> diff --git a/Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml b/Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml
> new file mode 100644
> index 000000000000..f3871c6b6afd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml
> @@ -0,0 +1,63 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/ptp/nxp,ptp-netc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NXP NETC V4 Timer PTP clock
> +
> +description:
> +  NETC V4 Timer provides current time with nanosecond resolution, precise
> +  periodic pulse, pulse on timeout (alarm), and time capture on external
> +  pulse support. And it supports time synchronization as required for
> +  IEEE 1588 and IEEE 802.1AS-2020.
> +
> +maintainers:
> +  - Wei Fang <wei.fang@....com>
> +  - Clark Wang <xiaoning.wang@....com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - pci1131,ee02
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +    description:
> +      The reference clock of NETC Timer, can be selected between 3 different
> +      clock sources using an integrated hardware mux TMR_CTRL[CK_SEL].
> +      The "ccm_timer" means the reference clock comes from CCM of SoC.
> +      The "ext_1588" means the reference clock comes from external IO pins.
> +      If not present, indicates that the system clock of NETC IP is selected
> +      as the reference clock.

	NETC timer reference clock have 3 clock inputs, sys: from RCiEP,
	ccm: from CCM of Soc, ext: from external IO pins. Internal have
	clock mux, only one of three need be provided. Default it is from
	RCiEP system clock.

> +
> +  clock-names:
> +    enum:
> +      - ccm_timer

look like just ccm is enough.

> +      - ext_1588

Missed kk's comments at v3.

"This should be just "ext"? We probably talked about this, but this feels
like you describe one input in different ways."

it should be "ext"!

Frank

> +
> +required:
> +  - compatible
> +  - reg
> +
> +allOf:
> +  - $ref: /schemas/pci/pci-device.yaml
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    pcie {
> +        #address-cells = <3>;
> +        #size-cells = <2>;
> +
> +        ptp-timer@18,0 {
> +            compatible = "pci1131,ee02";
> +            reg = <0x00c000 0 0 0 0>;
> +            clocks = <&scmi_clk 18>;
> +            clock-names = "ccm_timer";
> +        };
> +    };
> --
> 2.34.1
>